Minions are basically irrelevant power-wise. Towers are large sources of non-moving power early on, and become increasingly irrelevant.
So really the only power are your team's 5 champions, and you project by moving around. You most easily win by making the fight unfair in your favor, get a 2v1, 3v2, 5v4, etc. If one champion dies in vain late-game, the enemy team can often easily push towards a victory. Laying down vision wards is one of the most useful things you can do, to avoid or set up gankings.
The pro teams are very good at avoiding such unfair situations, so then you get team battles where all 10 champs are constantly re-positioning a little. Then one team sees an opportunity to jump on an enemy champ and kill quickly, or to just deal damage faster than the enemy team (some champs are better initiators, some are better at area of effect damage or stuns, etc.)
Overall I find the high-level skill is too much about clicking 50 times a minute and being hyper-aware CONSTANTLY, both of your immediate surroundings and the map as a whole. Knowledge leads to wins via ideal projection of power. What your toon does individually (feats of prowess) is of comparatively little importance.
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